Exactly. As ninjas always walk in the dark of night without fear, so should you. Else you're a nonja, which is like a ninja, but fake. That would be bad, because the real ninjas of the opposing ninja clan that you are impersonating would look for you.

And because ninjas know one billion ways of killing you, any nonja is at grave risk and thus need to avoid being ninjacided. Therefore the moral is don't be a nonja. It's bad.

I knew a guy in high school who lived in a house with woods behind it. One day he saw some young kids playing in his back yard, so he dressed as a ninja (I didn't say he was cool.) and ran out there to scare them off. It worked. The next day the same kids were playing in his yard, so he did it again. They ran into the bush and he chased them. They had brought their entire class with them and hidden in the bush. He had his butt kicked by 10 year olds. It was beautiful.

Moral of the story: don't be a poser. If you're a ninja, the world doesn't need to know it.